This image from Shaam News Network shows a Syrian military tank in Daraa Monday.AP

BEIRUT — Syrian rebels repelled a push Monday by government tanks into a key central town held by forces fighting President Bashar Assad’s regime as the country’s 11-month-old uprising looked increasingly like a nascent civil war.

The Britain-based Syrian Observatory for Human Rights said the attempt by regime forces to storm Rastan in the restive central province of Homs left at least three soldiers dead. Rastan has been held by the rebels since late January.

The town was taken by defectors twice in the past only to be retaken by Syrian troops. It is the hometown of former Defense Minister Mustapha Tlass, who held the post for more than three decades, mostly under Assad’s father and predecessor, the late Hafez Assad.

Calls to town’s residents could not get through on Monday and the telephone lines appeared to be cut, as they usually are during military operations.

“Troops maneuvered by moving on the northern edge of town then other forces attacked form the south,” said Rami Abdul-Rahman, who heads the Observatory. He added that hundreds of army defectors are in Rastan.

The Observatory also said that troops bombed the rebel-held Homs neighborhood of Baba Amr that has been under siege for more than a week. It reported clashes in the village of Busra al-Harir in the southern province of Daraa between troops and army defectors.

In the central city of Hama, a sniper shot dead a civilian, the group said.

The Syrian uprising began as mostly peaceful protests against Assad’s authoritarian regime, but it has turned increasingly militarized over the past few months in the face of a brutal military crackdown that has killed thousands of people.

Recently the conflict has taken on the dimensions of a civil war, with army defectors clashing almost daily with soldiers. The rebels have taken control of small swathes of territory in Homs and the northwestern province of Idlib that borders Turkey.

The Observatory, which has activists around Syria, said 45 vehicles, including tanks, arrived in the town of Jisr al-Shughour in Idlib region.

In Moscow, Russia’s foreign minister there must be a cease-fire in Syria before any peacekeeping mission could be sent to the country, rejecting calls for a joint Arab-U.N. force as premature.

Sergey Lavrov told reporters in Moscow that his country will study an Arab League proposal for a joint peacekeeping mission in Syria with the United Nations.

“We should first have peace, which would be supported,” Lavrov said at a news conference in Moscow with United Arab Emirates Foreign Minister Sheik Abdullah bin Zayed Al Nahyan.

Russia, along with China, have given support to Assad’s regime at a time when Syria is facing broad international isolation over a crackdown that has killed more than 5,400 people. The two powerful nations upset the U.S., Europe and many Arab countries earlier this month when they delivered a double veto to block a U.N. resolution calling on Assad to leave power.

Moscow’s stance is motivated in part by its strategic and defense ties, including weapons sales, with Syria. Russia also rejects what it sees as a world order dominated by the U.S. Last month, Russia reportedly signed a $550 million deal to sell combat jets to Syria.

He reiterated China’s stance that it wanted to see Syrian authorities and opposition forces “properly solve their disputes through dialogue.”

On Sunday, the 22-member Arab League called for the Security Council to create a joint Arab-U.N. peacekeeping force for Syria and urged Arab states to sever all diplomatic contact with Damascus in the League’s latest effort to bring an end to the violence.

The League also said it wanted to provide Syrian opposition groups with political and material support. It called for a halt to all diplomatic contacts with Syria and for referring officials responsible for crimes against the Syrian people to international criminal tribunals. It urged a tightening of trade sanctions previously adopted by the League that have not been fully implemented.

It urged Syrian opposition groups to unite ahead of a Feb. 24 meeting in Tunisia of the “Friends of Syria” group, which includes the United States, its European allies and Arab nations working to end the uprising against Assad’s authoritarian rule.

Britain’s Foreign Secretary William Hague said Monday that Britain would discuss the possibility of a joint-African Union and United Nations peacekeeping force for Syria ahead of the Tunisia talks.

“We will discuss urgently with the Arab League and our international partners the proposals for a joint Arab League and U.N. peacekeeping force,” he said. “Such a mission could have an important role to play in saving lives.”

Syria rejected the calls with state-run news agency SANA quoting an unnamed official as saying that the Arab League’s decisions are “a flagrant interference in the internal affairs and an infringement upon national sovereignty.”

The official said the Arab League decision “wound not dissuade Syria from continuing its responsibilities in protecting civilians and maintaining security and stability for its people.”

Assad’s regime has long blamed terrorists for the revolt that began with peaceful calls for democratic change but is morphing into a bloody, armed insurgency.